Lateral corticospinal tract

The lateral corticospinal tract is formed at the level of the of the medullary pyramids when the majority (90%) of descending corticospinal tract fibers decussate – the majority of the remaining non-decussating 10% of fibers form the much smaller anterior corticospinal tract, with only a few non-decussated fibers entering the lateral corticospinal tract 1,2.

The lateral corticospinal tract descends along the lateral funicular and then lies anterolateral to the dorsal horn. As it descends it deviates to the dorsolateral surface of the spinal cord, with individual fibers leaving the tract to synapse with grey matter motor neurones within the ventral horns. As more fibers leave the corticospinal tract commensurately diminishes in size. At approximately the fourth sacral level, it terminates entirely.